I need to connect a speed sensor module with an Arduino Due and calculate the speed of an approaching object.

the sensor is: http://www.limpkin.fr/index.php?post/2013/08/09/Making-the-electronics-for-a-%247-USD-doppler-motion-sensor

The sensor already output a signal that its' frequency represents the speed of the object.

I would really appreciate any help understating how can it be connected and operated by the Arduino without burning it, and how can I sample its output?

If more details are needed I'll be happy to supply.

Thanks.The module's connectors


The articles and tutorials I've read on the subject say that the HB100 module produces a very weak signal which needs to be amplified before your Arduino can read it. They recommend building an op amp. This post on the Arduino forums, for example: http://forum.arduino.cc/index.php?topic=61989.0

BUT looking at your picture and linked article, I find that your device already includes the signal amplification and filtering you need in the backpack board. I found the store page for this module, which has a more noob-friendly explanation. From what I gather:

  • VCC: provide the module with a 5v supply.
  • VOUT: analog reading of the amount of return signal being received. My guess is you could use this with analogRead() to get a rough estimate of the size or distance of the object being read. If you want only the speed reading, you don't need this pin.
  • FOUT: digital output of the speed that the sensor is reading. Thanks to @sachleen's link, you can use either pulseIn() or FreqCounter library to measure the frequency and then convert it to a MPH or KPH speed.
  • GND - ground, aka common, aka -.

So connect VCC to 5v, GND to ground, and FOUT to an input pin on your Arduino. If you use pulseIn(), frequency f = 1 / t, t being the return value from pulseIn(). If you use the FreqCounter library, it no doubt has documentation on its usage.

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